Three-dimensional modeling substrate



FIG. 1 is a perspective view of a three-dimensional modeling substrate, showing our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right side view thereof thereof;

FIG. 5 is a rear elevational view thereof;

FIG. 6 is a left side view thereof; and,

FIG. 7 is a bottom perspective view thereof. 

The ornamental design for a three-dimensional modeling substrate, as shown. 